1. Field of the Invention
The present invention relates to a super wide angle optical system, and more particularly, to a super wide angel optical system having a wider viewing angle in a certain direction, embodying subminiaturization, and manufactured at a low price.
2. Description of the Related Art
In general, in optical systems employed in a camera for automobile or a monitoring camera, to take an image of a wider range of the front, side, and rear, there are simultaneously required a wide angle lens having a horizontal viewing angle more than a certain degree and a lens with a subminiaturized size and light weight, which is employed in the optical system.
Particularly, optical systems employed to a camera for automobile should be designed to have a viewing angle of approximately 90 degrees from the ground to the horizon in a vertical direction and have a relatively wider viewing angle in a horizontal direction than the viewing angle in the vertical direction to provide a full visual field.
Lenses forming a general optical system are a circular shape rotationally symmetrical to an optical axis, and light incident on such optical system is also circular. Accordingly, when an optical system employing a wide angle lens rotationally symmetric is mounted on a camera, a lot of images in an unnecessary area is shown, and simultaneously, an unnecessary image area occurs on an image plane of an image sensor.
Also, when an optical system having a wide viewing angle is formed of rotationally symmetric lenses, a length of the optical system in an optical axis is increased and a diameter of a lens should be increased to provide a peripheral light amount, which obstacles subminiaturization of the optical system.